1. Field of the Invention
The present invention relates to an air wiper mechanism, and more particularly to an air wiper mechanism for a vehicle that produces plural air curtains using compressed air blast from an air blast nozzle.
2. Description of the Related Art
Conventionally, mechanical wipers are mounted to clear rain from the windscreen glass of a vehicle. Swinging the mechanical wiper obstructs somewhat the front view from a driver's seat, thus making comfortable driving difficult. The mechanical wiper has a disadvantage that oil film tends to adhere on the outer surface of the windscreen glass. The mechanical wipers have various problems such that it is difficult to wipe the corners of the windscreen glass which remain dirty and are directly exposed to rain water.
Under such a background, the present applicant proposed an improved air wiper. This invention was filed for Utility Model application on Jun. 21, 1977 in the Japan Patent Office and was registered as Registration No. 1501677 on Aug. 10 of 1983.
According to "Air Wiper for Vehicle" disclosed in the Utility Model Registration, an air nozzle is arranged to spout compressed air upward and in front of a windscreen glass to blow away rain water.
The structure is featured in that the air wiper includes a second nozzle group formed of plural nozzles and a second oscillating nozzle. Air ejected from the first nozzle group forms a first air curtain near a windscreen glass and substantially in parallel over the entire surface of the windscreen glass, and air ejected from a second oscillating nozzle forms a second air curtain more ahead of the first air curtain or at a position spaced further away from the windscreen glass. The two layer curtains formed on the front and rear planes can more certainly blow off rain water and provide a good front view from a vehicle on a rainy day.
As described above, the prior art air wiper has a doubled curtain formed of a first air curtain near to a windscreen glass and a second air curtain spaced away from the windscreen glass more than the first air curtain. However, when rain fall is heavy or a vehicle runs faster, the rain water blowing-off effect of the air curtain is not sufficient.
Moreover, since the strong wind streaming around the windscreen glass causes a large temperature difference between the outer side and the inner side of the windscreen glass, possible moisture condensation on the inner surface of the windscreen is produced. Particularly, the moisture condensation tends to occur more in cold seasons. There is another problem that since air from an oscillating air blast nozzle blows excessively and outward from both the sides of the windscreen glass, it may incidentally hit a person walking along a narrow street or passing by a parked vehicle.